94 UniversHii of Californid I'lihlicntidiis in Zodhii/n | Voi,. 22 



ing ill January, February, and Deconibcr, raic in March, April, Jul}', 

 August and October. Occurrence at Station II from April to Novem- 

 ber inclusive, but scattered and in small numbers with a maxinuun 

 in September. Limited to same period at Station III but regularly 

 recorded during most of IMay and .lunr with ma.xinuini in .May, 

 favored by sewage anil l)y a temiirraturi' ncai- 20° C. Stagnalidu 

 .seems to be detrimental. 



The jx'riods of regular oeeuri'eiiee were too short to give very well 

 iiiafkcd evidence of recurrent ])ulses. 



BracJiifjiiHs aiigularis caudatiis 1>. and Da. 



station 1 Station II Station III Daily Hourly 



Average 32.3,532 6.5,243 70,480 830,6.57 1,284,905 



Identification usually satisfactory. Sometimes hard to distinguish 

 from type form of B. aiigularis. The separate record of this variety 

 seems to have been worth while because of the tremendous emphasis 

 which it gives to the continuity in occurrence of the two forms. The 

 variety was almost wholly absent from the collections until the type 

 form had pa.ssed the spring nui.\inuuu. As the latter declined tiie 

 former increased until it entirely displaced the other. This was strik- 

 ingly true at all three stations. The variety also disappeared by No- 

 vember at all stations, at which time the type came in in small num- 

 bers for a few weeks. At Station I the maximum came on June 25 

 but was almost equalled in September. At lioth of the other stations 

 the maxima came in August. 



Recurrent pulses were very marked in the records for this form 

 as shown by the following table : 



Text Table 5 



station II 



July 12 

 Aug. 15 

 Sept. 20 

 Oft. 11 



Comparison with the table of ploiinan pulses at Station I shows 

 that four of the B. caudatus pulses correspond exactly while two oth- 

 ers are very close. It is thus evident that the relationship of occur- 

 rence of this organism to that of the chloroi>li\il bearers is about as 

 intimate as tlud of the whole ])loiman grouj). 



